An acceptor-substrate binding site determining glycosyl transfer emerges from mutant analysis of a plant vacuolar invertase and a fructosyltransferase

• DOI: 10.1007/s11103-008-9404-7
• Publication Date: 2008-09-27T05:08:00Z
• Authors: Denise Altenbach; Enrique Rudiño-Pi...; Clarita Olvera; Thomas Boller; Andres Wiemken; Tita Ritsema
• Keywords: Transferase; Hydrolase

Glycoside hydrolase family 32 (GH32) harbors hydrolyzing and transglycosylating enzymes that are highly homologous in their primary structure. Eight amino acids dispersed along the sequence correlated with either or glycosyltransferase activity. These were mutated onion vacuolar invertase (acINV) according to residue festuca sucrose:sucrose 1-fructosyltransferase (saSST) vice versa. acINV(W440Y) doubles transferase capacity. Reciprocally, saSST(C223N) saSST(F362Y) double hydrolysis. SaSST(N425S) shows a activity three four times its Interestingly, modeling acINV saSST 3D structure of crystallized GH32 indicates mutations saSST(N425S), acINV(W440Y), previously reported acINV(W161Y) reside very close together at surface entrance active-site pocket. Residues in- outside sucrose-binding box determine capabilities enzymes. Modeling suggests residues identify location for acceptor-substrate binding fructosyltransferases.